IF Construction and problem areas

[kjacobsen]

I am selling a bigger boat and looking for an IF. One area I'm unfamiliar with is hull and deck construction. Is the hull solid or cored? is the deck solid or cored? If it is cored, is is balsa or Airex (divinycell)? Are there any common problems such as hull blisters, hull/ deck joint, mast step problems, etc?

I would appreciate any comments or information.

Thanks and Tak

[maja]

The hull is solid and built from GRP, 2880 gram glass fibre per square meter.

The deck is cored. It is built from GRP, 2250 gram glass fibre per square metre and the laminate is cored by marine plywood of different thickness.

See drawing http://www.ifboat.com/teknik/R_1460.pdf

There are normally no blister problems, but sometimes small blisters in the gelcoat may occur. Anyhow, there are no structural problems and if the blisters have not shown up yet (in almost 30 years) they will probably not occur later.

There could occur som leakage between hull and deck, but this is easily fixed by replacing the rubber seal string ("on tube") from outside.

The mast beam may be damaged if there has been uncontrolled water leakage through the elecric contact at the side of the mast. This is easily recognized when rigging the boat, as the rig tension will not remain.

[francis]

I wonder what the 2880 grams per square meter would translate to in actual thickness measurements. Does anyone know how thick the hull is at the sheer and at the waterline?

[maja]

I will estimate the thickness to be about 6 mm. But it is of none importance as the glass fibre gives the strengh to the hull.

[francis]

I thought that the thickness reflected how many layers of glass fiber were used.

[kjacobsen]

I am still looking for the right IF boat. The information you all supplied will be of great help

Thank You,

Tak

K. Jacobsen

[maja]

I thought that the thickness reflected how many layers of glass fiber were used.

One glassfibre mat of 450 gram/square meter approximately corresponds to 1 mm of laminate thickness. So the hull laminate will most probably consist of six layers of 450 gram mats and one thinner (180 grammes) to smooth the surface of the hull underneath the gelcoat coating.

[francis]

Thanks Maja. I now understand